Window drafty cold draft — cold draft

Use only checks that match the exact appliance or system and its official guide.

1. Check 1

   On a windy, cold day, close and latch the window, then hold a thin tissue strip near the sash meeting rail, corners, frame-to-trim joint, and sill. Do not use a candle, lighter, or other flame to find the draft.

   Expected result: The tissue moves at a moving sash joint, at the stationary frame-to-wall edge, or not at all while the glass still feels cold.

   Next step: Mark the exact location and continue with the matching sash, frame, or condensation check. Do not seal a drainage path or cover a suspected leak before checking for water entry.

   Why this matters

   Why: Movement at the sash points to a seal or compression problem; movement at the frame-to-wall edge points to a rough-opening or trim air leak. No movement with cold glass makes a surface-temperature or humidity issue more likely than an airflow leak.

2. Check 2

   Inspect the visible weatherstripping, gaskets, sash corners, and latch side with the window closed; gently test whether the sash is held evenly against its seal without forcing the hardware.

   Expected result: A seal is flattened, split, missing, loose, or bypassed at a corner, or the sash appears evenly compressed and the latch works normally.

   Next step: Record the seal profile and window type before considering a compatible replacement weatherstrip. If the sash is warped, the latch will not hold it closed, or adjustment would require disassembly, arrange a window professional.

   Why this matters

   Why: A damaged or poorly compressed seal can let cold outdoor air bypass the closed sash. An intact, evenly compressed seal makes the moving joint less likely as the primary leak, so the frame junction or another window may need attention.

3. Check 3

   From inside and from ground level outside, inspect the stationary frame, trim, sill, and visible flashing for open joints, peeling sealant, water stains, soft trim, or a gap where the frame meets the wall. Do not climb or remove exterior cladding for this check.

   Expected result: A gap or water stain is concentrated at the frame-to-wall junction, or the visible frame and surrounding finish are dry and intact.

   Next step: Photograph the location and arrange a qualified window, siding, or weatherization inspection before applying foam or caulk into an unknown drainage path. Keep the interior dry while the cause is investigated.

   Why this matters

   Why: A frame-to-wall gap can allow wind and rain behind the trim and is not the same repair as replacing sash weatherstripping. A dry, intact surface makes a visible installation leak less likely but cannot rule out a concealed gap.

4. Check 4

   Measure indoor relative humidity with a humidity meter and note whether moisture appears on the room-side glass after showers, cooking, drying clothes, or during colder weather.

   Expected result: Humidity is persistently high or condensation follows moisture-producing activities, or the glass stays dry while a tissue confirms moving air at a joint.

   Next step: Vent moisture-producing rooms outdoors and use appropriate dehumidification when needed; repair the confirmed leak separately. If condensation persists or affects the wall, arrange a building-envelope assessment.

   Why this matters

   Why: High humidity or activity-linked condensation can make cold glass wet even without a draft. A confirmed airflow path with dry glass keeps air leakage as the primary issue, while both conditions can coexist.

5. Check 5

   Open and close the window once while watching the sash, hinges or tracks, locking points, and glass from inside; stop if the hardware binds or the glass is cracked.

   Expected result: The sash does not sit square, the latch cannot pull it evenly closed, the frame is damaged, or the window operates smoothly and seals evenly.

   Next step: Do not force or plane the sash as a quick fix. Have a qualified window professional assess alignment, hardware, frame, and any insulated-glass failure before ordering parts.

   Why this matters

   Why: A warped sash, damaged frame, or failed latch can create a persistent perimeter leak and may make weatherstripping ineffective. Smooth operation and even closure shift attention back to the identified seal or rough-opening gap.